Noise is a factor to consider in any imaging situation, to a smaller or greater extent. For that reason the area is well researched and there are numerous techniques for noise reduction for most types of noise. Furthermore this makes it relevant to define the type of noise being the prime candidate for the invention according to the present application, namely various types of Fixed Pattern Noise (FPN) to be further specified in the Detailed Description. The invention will be described and explained in the context of readout noise, yet other types of Fixed Pattern Noise would also be suppressed. The present invention is particularly useful in connection with FPN being generated during readout, FPN that varies slowly over time, and FPN having a regionally clustered appearance such that it comprises edges. This will be explained further in the detailed description. Furthermore, the invention is particularly well-suited for thermal cameras using microbolometers, partially due to their specific properties in terms of various types of noise and since the signal-to-noise level may often be low.